A transistor has three terminals: collector, emitter, and base. An N-type semiconductor is inserted between two P-type semiconductors to create PNP transistors. Transistors are mostly used to amplify and switch the electrical signal.
PNP Bipolar Transistors
The device that controls the much larger current flow from the emitter to the collector by using a very small current and negative voltage on the base is known as a PNP bipolar transistor. In the PNP transistor, the emitter has a higher positive charge than the base and collector. The configuration produced by PNP is positive-negative-positive:
The above figure shows the schematic and circuit diagram of the PNP transistor. The above figure shows that the base terminal is always positive with respect to the emitter, and voltage VBE is applied between the base and emitter:
In the above figure, the emitter is connected to VCC with respect to the load resistance RL and helps to limit the current flow through the load. The resistance RB limits the base current. The base must be more negative with respect to the emitter for the normal operation of the transistor. The formulas of base emitter and collector are given as:
The characteristic curve of both PNP and NPN is the same, the only difference is the PNP rotated by 1800 to overcome the effect of current and voltage:
The above figure is the characteristic curve of a PNP transistor, it represents the emitter voltage that is directly related to the emitter current by fixed the voltage VBC.
Example of PNP Bipolar Transistors
The voltage drop of 1 k-ohm resistor is 3V, find base current Ib, the value of current IC is given as:
Rearrange it
Now find the base current
Conclusion
An N-type semiconductor is inserted between two P-type semiconductors to create PNP transistors. Transistors are mostly used to amplify and switch the electrical signal. The configuration produced by PNP is positive-negative-positive.
